Premiums are almost identical for both options (I save my premiums on option 1, but she pays a spousal surcharge).
One would think that having an extra policy is always better, but her policy has better terms (deductible, co-pays) so perhaps I lose by having hers secondary? I have the exact same question with dental plans (both free, hers better, should I enroll with my employer or waive?)

Thanks for helping with this. I usually almost never use my health insurance; I've had an accident and paid ~10K of balance billing bills in the last 6 months. There's a chance I will still need some services in 2019, so I'm looking into my options.

I looked into this recently when my son got a job, his employer offered health insurance but he was still covered under my wife's plan, my wife's plan is better. I think it may make a difference if they are both with the same insurance carrier. Both policies are with Kaiser, we called them and there is a benefit to have 2 policies, the lesser one as backup. As I recall for Kaiser, at a minimum it eliminated the co-pay.

I looked into this recently when my son got a job, his employer offered health insurance but he was still covered under my wife's plan, my wife's plan is better. I think it may make a difference if they are both with the same insurance carrier. Both policies are with Kaiser, we called them and there is a benefit to have 2 policies, the lesser one as backup. As I recall for Kaiser, at a minimum it eliminated the co-pay.

You may want to contact your insurance carrier.

Thank you .In my case it is not the same carrier (UHC & Anthem). Also, I agree that the lesser one as a backup is a good idea; in my case, the lesser one would be my primary insurance. So it's not exactly a backup, and I don't understand how they work jointly (could I actually get lesser benefits by having both, given that the lesser one picks up the bill first?).

Primary coverage will determine what they will pay, then do so. The secondary coverage will then determine what they would have paid if they were the only coverage, then adjust to account for the fact that the primary payment has already been made.

Dual coverage almost always means lower out of pocket, but you need to consider your share of premiums of course. Some employers will offer you some additional $ to opt out of their insurance.

For each policy (or claim), there will be a primary payer and a secondary payer. Whichever is considered primary will pay first, according to its rules and benefits. Then the secondary will evaluate the claim (knowing it is a secondary payer) according to its rules. The primary payer should be able to forward the claim to the secondary for consideration directly.

Whether this is financially beneficial to you depends on many factors - which policy is primary vs secondary for each claim, what does the secondary policy cover specifically? What do you pay for the premiums for the 'secondary' policy vs what costs does it pay (as secondary insurance). Calculating this will be a nightmare and highly dependent upon your actual claims and medical needs. If you are paying $4000 per year for the 'secondary' policy but only getting $2500 of payout, then it is not worthwhile -- but to know these numbers will be daunting! And next year your needs may be different!